Fix compilation with old ICC version (use C99 types instead of C++11 ones)

Eigen/src/Core/util/Meta.h

diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 604f509..01a9647 100644
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -28,8 +28,8 @@
   */
 
 #if EIGEN_COMP_ICC
-typedef std::intptr_t IntPtr;
-typedef std::uintptr_t UIntPtr;
+typedef intptr_t IntPtr;
+typedef uintptr_t UIntPtr;
 #else
 typedef std::ptrdiff_t IntPtr;
 typedef std::size_t UIntPtr;